In a typical nuclear fission reaction, a heavy nucleus decays into daughter nuclei which are lighter and have higher binding energy per nucleon. For example:

U-235 + n --> U-236 --> Ba-141 + Kr-92

In the Atomic-mass vs. Binding-Energy-per-Nucleon graph, both Ba and Kr are further up the curve towards Fe-56.

Do fission reactions exist where one of the nuclei is "over the hump"?

For example, could one daughter nucleus of fission be F-19? If not, why not?

If yes, could one daughter nucleus have lower binding energy per nucleon than the original atom (even if the total binding energy per nucleon increases overall?)

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    $\begingroup$ In actinide fission, such light nuclei seem to be missing from the daughter mass spectrum. $\endgroup$ – rob May 17 '17 at 20:09
  • $\begingroup$ @rob I will generally agree, with a caveat - when plotted on a log scale (such as in Selby et al., Nuclear Data Sheets 11 2891-2922 (2010)), they show the probability dropping below $10^{-6}$ at about mass 66. At Mass 76 it is about $10^{-2}$ So, it is conceivable that there could be some extremely low yield around Fe-56, but it would be $10^{-10}$ or lower. $\endgroup$ – Jon Custer May 17 '17 at 22:07
  • $\begingroup$ So when I look at these yield tables, it means that there is a non-negligeable probability of having Helium and Hydrogen isotopes as fission products (which would have a lower binding energy per nucleon compared to Uranium)? $\endgroup$ – Massagran May 18 '17 at 2:12

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